II. To evaluate the efficacy of treatment with nivolumab and veliparib in this population by objective response rate (ORR, defined as partial response [PR] + complete response [CR]), clinical benefit rate (CBR, defined as stable disease [SD] for >= 12 weeks, PR, + CR), and progression free survival (PFS, defined as the time from treatment initiation to documented disease progression) using Response Evaluation Criteria in Solid Tumors (RECIST) criteria version (v)1.1 or Lugano criteria.